#include <bits/stdc++.h>
using namespace std;
#define PI 3.1415926
#define   SQUARE(x) ((x)*(x))
//double SQUARE(double x) { return x*x;}

int main()
{
	int x, y, z;
	double x2, b;
	char c;
	scanf("%d%d%d",  &x, &y, &z);

	printf("%s", (x+y>z && x+z>y && y+z>x) ? "yes" : "no");

  return 0;
}
